This section is intended to provide a background or context to the invention recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Drilling systems are generally known to include a vertical drill tower (e.g. mast, etc.) constructed from structural members such as steel beams and reinforcing supports. The drill tower is often coupled to a mobile platform (e.g. which along with other components typically form a drilling rig) for positioning the drill tower in a desired location to conduct a drilling operation. The drill tower is often equipped with a drill carousel which is structured and adapted to support a drill string formed from a combination of drill extenders (e.g. drill rods, drill pipes, etc.). The drill carousel is used to selectively add the drill extenders to the drill string for drilling a hole having a desired depth. The drill carousel is intended to allow a drilling operation to progress into the drill hole by making readily available a continuous string of drill extenders as needed for advancing a drilling tool into a drill hole.
The initial (e.g. the first and therefore lowermost) drill extender in the drill string is configured to receive a drilling tool at its lower end to conduct the drilling operation. The drilling tool is usually a drill bit (such as a tricone drill bit) or a ‘down the hole’ hammer (e.g. hammer tool—for fracturing substrate such as rock formations, etc.). After a certain amount of usage in the drilling operation it is often desirable or necessary to change (e.g. remove, replace, change-out, etc.) the drilling tool due to (for example) accumulated wear of an in-service drill bit, the need to change between a drill bit and a hammering tool (or vice versa), etc. In order to minimize downtime in the drilling operation due to change-out of drilling tools, mechanisms may be provided to facilitate removing one drilling tool from the end of the drilling string and replacing it with another drilling tool from a storage or supply location.
One example of such a mechanism is shown in U.S. Pat. No. 3,977,480 which generally shows a magazine for storing drill bits and a swingable arm to facilitate transfer of the drill bits between the magazine and the drill string. Another example of such a mechanism is shown in U.S. Patent Application Publication No. 2006/0162963 which generally shows a magazine for storing drill bits and a swingable arm having a rotatable carousel on one end to facilitate transfer of the drill bits between the magazine and the drill string. Another example is U.S. Pat. No. 7,886,846 which discloses a rotary carousel device. However, the disclosed mechanisms generally require a large amount of space to accommodate swinging of the arm and/or rotation of the carousel, and are not readily adaptable for use in an automated or semi-automated manner to improve service access from the ground to minimize downtime during change-outs and to minimize the number of personnel required at the drilling rig.